The present invention relates broadly to a shaft position encoder system, and in particular to a radial optical encoder apparatus for precision shaft angle measurements.
In the prior art, the most frequently utilized conventional optical encoders which were used to measure shaft angles usually required code discs or code drums. The use of code discs/drums dictated the need for a very close spacing and positional stability between the code pattern material and, either or both, the light source and the sensor. Furthermore, the operation of the prior art encoding system, generally, depended upon the use of a reflective or transmissive code wheel. The present invention provides an optical encoder apparatus which is capable of precision measurements in an environment of relatively large end play, in/out radial shifts, side to side translations and some angular shifts in axes.